The conversion of alternating current to direct current is called rectification, and the conversion of direct current to alternating current is called inverter. Inverting is much more complicated than rectifying.
DC to AC power converter equipment used is called "inverter" principle, basic is to use direct current (dc) to the inverter output transistor, up in the tube back to the way of transformer and other components on the tube to form the positive feedback and make the tube's "shock" (initial) into ac output current, if you need to compare "strictly" output current waveform, has to access the electronic components, composition of output waveform shaping circuit.
DC to AC power converter is used to convert AC power to DC power. Virtually all electronic devices require converters. They are also used to detect am radio signals and to provide polarized voltages for welding. The converter can be used for dc-dc conversion. Here, the inverter converts the DC to AC and then USES a transformer to convert it back to DC.
There are two kinds of methods, one is the first by way of SPWM, the sine wave modulation (if square wave can also, this step can be omitted), and then through a switch H bridge output voltage polarity, this requires a synchronous switch and H bridge SPWM circuit, technically complicated but it seems that the efficiency of this approach is very high, so a lot of inverter are this way. There is also a kind of circuit is relatively simple, similar to the inverter circuit of electric mosquito bat, which consists of a transformer with multiple windings and a small number of transistors to form a semi-bridge inverter circuit that can self-oscillate. The efficiency of this method is relatively low, and it is generally only for small power applications.